The present invention relates generally to an apparatus for conveying passengers and, in particular, to a system for conveying passengers in cars travelling in intersecting vertical and horizontal elevator shafts.
A passenger conveying system is illustrated and described in the U.S. Pat. No. 3,658,155. A plurality of self-propelled cars move vertically in the same elevator shaft and can move laterally from the shaft at any floor. The drive means mounted on each car is a motor and a chain transmission on an axially displaceable shaft with toothed pinions at the end. The pinions engage a multitrack toothed rack, wherein one track extends only vertically, another leads horizontally to the left at floors and a third leads horizontally to the right at floors. The appropriate travel track is chosen by the extent of the axial displacement of the pinion shaft. The car is suspended by the drive and is guided in the shafts by additional support wheels at the four corners. Special mechanical equipment keeps the toothed pinions in engagement during a change in direction of the car.
This system requires many precision mechanical parts; in particular, the different toothed racks are costly. Furthermore, corresponding safety equipment must be provided in case of breakage of a drive means part.
Another drive means for a passenger conveying car is shown in the German Patent Specification No. 39 39 762. The car drive includes an endless toothed belt which has teeth formed on both sides. A drive wheel and a deflecting or tensioning roller engage the inwardly directed teeth. The outwardly directed teeth engage a toothed rack which also serves to guide the car in a vertical path. Due to the tooth shapes of the toothed rack and of the toothed belt, a contact pressure device must be provided to force the belt against the rack. This contact pressure device consists of another toothed belt with a number of pressure rollers or, in a different form, several pressure rollers arranged in a row in a support.
This system requires a relatively fine toothed rack and an additional contact pressure device. Safety devices are not used since the system is installed at a building site. However, safety devices would be required for regular passenger transport use.